The use of personal communication devices has increased astronomically over the last two decades. The penetration of mobile devices (user equipment or UEs) in modern society has continued to drive demand for a wide variety of networked devices in a number of disparate environments. The use of networked UEs using 3GPP systems has increased in all areas of home and work life. An increasing number of mobile services involve accurate determination of the UE position. One of the most common methods of location is through the use of a Global Positioning System (GPS) or Global Navigation Satellite System (GNSS). In addition to providing a location for commercial and personal applications, GPS/GNSS-enabled UEs may be used by emergency services to obtain information as to the position of the UE as part of the processing of an emergency call (E911 services). While position determination for E911 services is mandated by the Federal Communications Commission (FCC), in a number of cases, position determination based on satellite (GPS/GNSS) signals is ineffective. In particular, GPS or GNSS may not be available in certain areas due to blockage of the satellite signals, such inside buildings or other areas where the UE may be unable to detect signals from a sufficient number of satellites. This problem may only increase as the FCC guidelines become more stringent, with 67% of outdoor E911 communications presently mandated to be located with 50 m accuracy and 80% of the calls with 150 m accuracy (rising to 90% by 2020). Moreover, the FCC is proposing to extend E911 location determination to indoor locations and further require vertical location information within 3 meters of the caller for 67% of indoor E911 communications (rising to 80% by 2020).
The most recent release (Release 13) of the 3GPP standard for Long-Term-Evolution (LTE) networks contains updated requirements for position determination that are difficult to obtain due to the current positioning capabilities of networks. It would thus be desirable to improve positioning accuracy and enable vertical domain positioning of UEs.